January 25, 2018

Translation of Japanese J-Ships Article which uses Submarine Matters Articles

Tanaka (in a comment here) has kindly translated (from Japanese to English) an article by Isaku Okabe (a popular Japanese military critic) in the J-Ships February 2018 issue. J-Ships is a popular Japanese maritime magazine.Isaku Okabe's article concerns the Soryu Mk.2's improved, more stealthy, snorting/snorkeling performance. The information on the Soryu Mk.2 performance is based on Submarine Matters'articles written by Anonymous and Pete ( here, here and here and especially here, hereandhere ) .Tanaka's Translation [with some further Pete translation] is:"THE INCREASING CAPABILITY OF
STEALTH CRUISING THANKS TO THE LONGER UNDERWATER DURATION".

"There are some estimations of performance comparison between [the current] Soryu class [Mk. 1] and [submarine number] 27SS [see TABLE below] in a blog [Submarine Matters] written by a foreigner [ :) ] who is familiar with submarine matters.In the blog, 27SS is called "Soryu Mk.2" and its maximum period of continuous [fully submerged] cruising at a speed of 4 knots is estimated to be 7~9 days compared to that of Soryu's 3~3.5days.The blog says the general period of continuous [Soryu Mk.2] fully submergedcruising will increase to 6~8 days though the current Soryu class can cruise only 1~1.5 days.The so called "Soryu Mk.2" will be able to conduct secret patrols without snorting for a much longer time. In regard to cruising at a speed of 18 knots, "Soryu Mk.2" will be able to do it continuously for 3~4 hours which is 3~4 times longer than current Soryu's.

The time required for charging batteries for the current Soryu Mk. 1 is estimated to be 5~10 hours, whereas the "Soryu Mk.2" needs just 1~2 hours, which makes the latter much more stealthy.Supposing the mission period is 60 days, the "Soryu Mk.2" [needs to snort] 8~10 times compared to 40~60 times for the Soryu Mk.1. Snorting [with loud diesels running] reduces stealthiness - so a submarine needs to move out of its operational area to be safe.[Lithium-ion Batteries (LIBs)] can reduce the number and length of snorting times which increases the stealthy operational time. This results in much more efficient use of submarines.It goes without saying that these are estimations by a foreigner [ but kindly provided by Anonymous ] and no one knows if they are correct or not. But at least they can be good indicators to infer the progress of submarines using LIBs [rather than shorter operating Lead-acid Batteries (LABs)] .

Converting from [the Soryu Mk.1's] AIP + LABs to [the Soryu Mk.2's] LIBs is not as simple as just changing the type of batteries. Many parts of the submarine need to be modified such as whole power system and safety management system for the realistic and safe use of LIBs.The 11th [27SS] and 12th [28SS] Soryu class submarines, which correspond to what the foreigner calls "Soryu Mk.2", will undergo major battery-electrical system conversions but not other major changes. Soryu Mk.2's hulls, weapons, sensors and control systems remain almost the same as current Soryu class." [The author, Okabe, did not mention the major change to the more powerful, storm tolerant, snorkel system. Maybe that will be introduced on the Soryu Mk.3?].TABLE - SORYU & Oyashio Program as at January 25, 2018

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